Six children with morphological hair-shaft abnormalities and neurological disease are presented, including two with Pollitt syndrome, one with biotin deficiency, two with Menkes diseases and one with argininosuccinic aciduria. The child with biotin deficiency grew normal hair following oral biotin therapy. Although the hair-shaft abnormalities may be seen with light microscopy (LM), they are best visualised with scanning electron-microscopy (SEM). Pili torti may be mistaken for monilethrix by LM, but SEM shows the true defect. A review of the literature shows that these hair-shaft abnormalities (trichorrhexis nodosa, monilethrix and pili torti) are not specific or pathognomonic, but do indicate a group of neurological disorders, including potentially treatable inborn errors of metabolism. The term 'neurotrichosis' is suggested to classify this group of disorders.